using System.Linq;
using UnityEngine;

namespace S3.Modules.PhysicsOptimizer;

// Renders the Physics Optimizer settings as the body of its foldout in the S³
// settings panel. Writes both the persisted settings and the runtime statics on
// every change, then persists via PhysicsOptimizerModule.Persist().
static class PhysicsSettingsUI
{
    static readonly int[] ResyncOptions = { 1, 2, 4, 8, 16 };
    static readonly string[] ResyncLabels = { "1/1 (max quality)", "1/2", "1/4 (default)", "1/8", "1/16" };

    static string _addInput = "";
    static string _toRemove = null; // deferred to avoid mutating list during enumeration

    public static void Draw()
    {
        PhysicsSettings s = PhysicsOptimizerModule.Settings;
        bool changed = false;
        GUILayout.BeginVertical();

        // ── LOD Fast-Path ─────────────────────────────────────────────────────────
        GUILayout.Label("<b>LOD Fast-Path</b>", GUILayout.ExpandWidth(false));
        GUILayout.Space(4f);

        bool newEnabled = GUILayout.Toggle(s.OptimizerEnabled,
            " Enabled  (skips expensive 3D updates for cars far from camera)");
        if (newEnabled != s.OptimizerEnabled)
        {
            s.OptimizerEnabled = newEnabled;
            ConsistLOD.Enabled = newEnabled;
            changed = true;
        }

        GUILayout.Space(6f);

        // Distance threshold slider
        GUILayout.BeginHorizontal();
        GUILayout.Label($"Distance threshold:  {s.DistanceThreshold:F0} m", GUILayout.Width(220f));
        float newDist = GUILayout.HorizontalSlider(s.DistanceThreshold, 5f, 200f, GUILayout.Width(200f));
        GUILayout.EndHorizontal();
        GUILayout.Label("  Cars farther than this from the camera use dead-reckoning.", GUI.skin.label);

        if (Mathf.Abs(newDist - s.DistanceThreshold) > 0.5f)
        {
            s.DistanceThreshold          = Mathf.Round(newDist);
            ConsistLOD.DistanceThreshold = s.DistanceThreshold;
            changed = true;
        }

        GUILayout.Space(6f);

        // Resync quality radio buttons
        GUILayout.Label("Resync quality (fraction of far cars fully updated per tick):");
        GUILayout.BeginHorizontal();
        for (int i = 0; i < ResyncOptions.Length; i++)
        {
            bool selected = s.ResyncInterval == ResyncOptions[i];
            if (GUILayout.Toggle(selected, ResyncLabels[i], GUI.skin.button, GUILayout.Width(130f)) && !selected)
            {
                s.ResyncInterval          = ResyncOptions[i];
                ConsistLOD.ResyncInterval = s.ResyncInterval;
                changed = true;
            }
        }
        GUILayout.EndHorizontal();
        GUILayout.Label("  Lower = smoother visuals; higher = cheaper. Cost spread evenly via stagger.", GUI.skin.label);

        GUILayout.Space(12f);

        // ── Auto Freeze ───────────────────────────────────────────────────────────
        GUILayout.Label("<b>Auto Freeze</b>  (replaces stock optimizer)", GUILayout.ExpandWidth(false));
        GUILayout.Space(4f);

        bool newAF = GUILayout.Toggle(s.AutoFreezeEnabled,
            " Skip Verlet tick for consists that are far away and nearly stopped");
        if (newAF != s.AutoFreezeEnabled)
        {
            s.AutoFreezeEnabled              = newAF;
            ConsistFreezer.AutoFreezeEnabled = newAF;
            changed = true;
        }

        if (s.AutoFreezeEnabled)
        {
            GUILayout.Space(4f);

            GUILayout.BeginHorizontal();
            GUILayout.Label($"Freeze distance:  {s.AutoFreezeDistance:F0} m", GUILayout.Width(200f));
            float newFDist = GUILayout.HorizontalSlider(s.AutoFreezeDistance, 50f, 1000f, GUILayout.Width(200f));
            GUILayout.EndHorizontal();
            GUILayout.Label("  Consists with no car closer than this are eligible to freeze.", GUI.skin.label);
            if (Mathf.Abs(newFDist - s.AutoFreezeDistance) > 1f)
            {
                s.AutoFreezeDistance              = Mathf.Round(newFDist);
                ConsistFreezer.AutoFreezeDistance = s.AutoFreezeDistance;
                changed = true;
            }

            GUILayout.Space(4f);

            GUILayout.BeginHorizontal();
            GUILayout.Label($"Speed threshold:  {s.AutoFreezeSpeedThreshold * 2.23694f:F1} mph", GUILayout.Width(200f));
            float newSpd = GUILayout.HorizontalSlider(s.AutoFreezeSpeedThreshold * 2.23694f, 0f, 10f, GUILayout.Width(200f));
            GUILayout.EndHorizontal();
            GUILayout.Label("  Consist must be slower than this to be eligible.", GUI.skin.label);
            float newSpdMs = newSpd / 2.23694f;
            if (Mathf.Abs(newSpdMs - s.AutoFreezeSpeedThreshold) > 0.01f)
            {
                s.AutoFreezeSpeedThreshold              = newSpdMs;
                ConsistFreezer.AutoFreezeSpeedThreshold = s.AutoFreezeSpeedThreshold;
                changed = true;
            }
        }

        GUILayout.Space(12f);

        // ── Locomotive Exclusions ─────────────────────────────────────────────────
        GUILayout.Label("<b>Locomotive Exclusions</b>", GUILayout.ExpandWidth(false));
        GUILayout.Space(4f);

        bool newExLOD = GUILayout.Toggle(s.ExcludeLocosFromLOD, " Exclude locomotives from LOD fast-path");
        if (newExLOD != s.ExcludeLocosFromLOD)
        {
            s.ExcludeLocosFromLOD          = newExLOD;
            ConsistLOD.ExcludeLocomotives  = newExLOD;
            changed = true;
        }

        bool newExFreeze = GUILayout.Toggle(s.ExcludeLocosFromFreeze, " Exclude locomotives from Auto Freeze");
        if (newExFreeze != s.ExcludeLocosFromFreeze)
        {
            s.ExcludeLocosFromFreeze             = newExFreeze;
            ConsistFreezer.ExcludeLocomotives    = newExFreeze;
            changed = true;
        }

        GUILayout.Space(12f);

        // ── Road Number Filter ────────────────────────────────────────────────────
        GUILayout.Label("<b>Road Number Filter</b>", GUILayout.ExpandWidth(false));
        GUILayout.Space(4f);

        bool newBlEnabled = GUILayout.Toggle(s.BlacklistEnabled, " Enable road number filter");
        if (newBlEnabled != s.BlacklistEnabled)
        {
            s.BlacklistEnabled          = newBlEnabled;
            ConsistLOD.BlacklistEnabled = newBlEnabled;
            ConsistLOD.InvalidateConsistCache();
            changed = true;
        }

        if (s.BlacklistEnabled)
        {
            GUILayout.Space(4f);

            // Mode toggle
            GUILayout.BeginHorizontal();
            GUILayout.Label("Mode:", GUILayout.Width(45f));
            if (GUILayout.Toggle(s.IsBlacklist, " Blacklist  (listed consists skip optimizer)",
                GUILayout.ExpandWidth(false)) && !s.IsBlacklist)
            {
                s.IsBlacklist          = true;
                ConsistLOD.IsBlacklist = true;
                ConsistLOD.InvalidateConsistCache();
                changed = true;
            }
            GUILayout.EndHorizontal();
            GUILayout.BeginHorizontal();
            GUILayout.Space(45f);
            if (GUILayout.Toggle(!s.IsBlacklist, " Whitelist  (only listed consists use optimizer)",
                GUILayout.ExpandWidth(false)) && s.IsBlacklist)
            {
                s.IsBlacklist          = false;
                ConsistLOD.IsBlacklist = false;
                ConsistLOD.InvalidateConsistCache();
                changed = true;
            }
            GUILayout.EndHorizontal();

            GUILayout.Space(6f);

            // Add entry
            GUILayout.BeginHorizontal();
            GUILayout.Label("Road number:", GUILayout.Width(110f));
            _addInput = GUILayout.TextField(_addInput, GUILayout.Width(160f));
            if (GUILayout.Button("Add", GUILayout.Width(50f)))
            {
                string trimmed = _addInput.Trim();
                if (trimmed.Length > 0 && !s.RoadNumberList.Contains(trimmed))
                {
                    s.RoadNumberList = s.RoadNumberList.Append(trimmed).ToArray();
                    SyncList(s);
                    changed = true;
                }
                _addInput = "";
            }
            GUILayout.EndHorizontal();
            GUILayout.Label("  Enter the full display name as shown in-game (e.g. \"UP 1234\").", GUI.skin.label);

            GUILayout.Space(4f);

            // Current entries
            if (s.RoadNumberList.Length == 0)
            {
                GUILayout.Label("  (no entries)", GUI.skin.label);
            }
            else
            {
                foreach (string name in s.RoadNumberList)
                {
                    GUILayout.BeginHorizontal();
                    GUILayout.Label(name, GUILayout.Width(180f));
                    if (GUILayout.Button("Remove", GUILayout.Width(70f)))
                        _toRemove = name;
                    GUILayout.EndHorizontal();
                }

                // Apply deferred removal (can't mutate inside foreach)
                if (_toRemove != null)
                {
                    s.RoadNumberList = s.RoadNumberList.Where(n => n != _toRemove).ToArray();
                    SyncList(s);
                    _toRemove = null;
                    changed = true;
                }
            }
        }

        GUILayout.Space(12f);

        // ── Debug Visualization ───────────────────────────────────────────────────
        GUILayout.Label("<b>Debug Visualization</b>", GUILayout.ExpandWidth(false));
        GUILayout.Space(4f);
        GUILayout.Label("  Tints car models by physics state. Useful for verifying LOD and freeze behaviour.", GUI.skin.label);
        GUILayout.Space(4f);

        bool newHF = GUILayout.Toggle(s.DebugHighlightFrozen,   " Highlight frozen cars  (yellow)");
        if (newHF != s.DebugHighlightFrozen)   { s.DebugHighlightFrozen   = newHF; changed = true; }

        bool newHFP = GUILayout.Toggle(s.DebugHighlightFastPath, " Highlight fast-path cars  (cyan)");
        if (newHFP != s.DebugHighlightFastPath) { s.DebugHighlightFastPath = newHFP; changed = true; }

        bool newHFU = GUILayout.Toggle(s.DebugHighlightFullPath, " Highlight full-accuracy cars  (magenta)");
        if (newHFU != s.DebugHighlightFullPath) { s.DebugHighlightFullPath = newHFU; changed = true; }

        GUILayout.EndVertical();

        if (changed)
            PhysicsOptimizerModule.Persist();
    }

    static void SyncList(PhysicsSettings s)
    {
        ConsistLOD.RoadNumberList.Clear();
        foreach (string n in s.RoadNumberList)
            ConsistLOD.RoadNumberList.Add(n);
        ConsistLOD.InvalidateConsistCache();
    }
}